Weight!

So i just weighed my beautiful male chinchillas today, and they are both 3 months and 1 week old, they are both around 230-248 Grams, the Standard being 248 and the Mosaic 232.

Is this too low? I've been researching a lot and it says they should be between 330-600.

I really need to know if this is fine or not and how regularly i should weight them.

I'm thinking i should weigh them again next week.